Built to last: Uniform LiNi0.5Mn1.5O4 hollow microspheres and microcubes (see picture; scale bars: 1 μm) with nanosized building blocks have been synthesized by a facile impregnation method followed by a simple solid‐state reaction. The resultant LiNi0.5Mn1.5O4 hollow structures deliver a discharge capacity of about 120 mA h g−1 over prolonged cycling and exhibit excellent rate capability.

Auf Dauer angelegt: Einheitliche, hohle Mikrokugeln und ‐würfel aus LiNi0.5Mn1.5O4 (siehe Bild; Skalierung: 1 μm) aus nanoskaligen Bausteinen wurden durch eine einfache Imprägnierungsmethode, gefolgt von einer simplen Festkörperreaktion synthetisiert. Die Hohlstrukturen weisen eine Entladungskapazität von 120 mA h g−1 über viele Zyklen auf und zeigen exzellente Entladungsraten.

No abstract

Uncontrolled growth of Zn dendrites and side reactions are the major restrictions for the commercialization of Zn metal anodes. Herein, we develop a TiO x /Zn/N-doped carbon inverse opal (denoted as TZNC IO) host to regulate the Zn deposition. Amorphous TiO x and Zn/N-doped carbon can serve as the zincophilic nucleation sites to prevent the parasitic reactions. More importantly, the highly ordered IO host homogenizes the local current density and electric field to stabilize Zn deposition. Furthermore, the three-dimensional open networks could regulate Zn ion flux to enable stable cycling performance at large current densities. Owing to the abundant zincophilic sites and the open structure, granular Zn deposits could be realized. As expected, the TZNC IO host guarantees the steady Zn plating/stripping with a long-term stability over 450 h at the current density of 1 mA cm À 2 . As a proof-of-concept demonstration, a TZNC@Zn j j V 2 O 5 full cell shows long lifespan over 2000 cycles at 5.0 A g À 1 .

Single-atom catalysts (SACs) are being pursued as economical electrocatalysts. However, their low active-site loading, poor interactions, and unclear catalytic mechanism call for significant advances. Herein, atomically dispersed Ni/Co dual sites anchored on nitrogen-doped carbon (a-NiCo/NC) hollow prisms are rationally designed and synthesized. Benefiting from the atomically dispersed dual-metal sites and their synergistic interactions, the obtained a-NiCo/NC sample exhibits superior electrocatalytic activity and kinetics towards the oxygen evolution reaction. Moreover, density functional theory calculations indicate that the strong synergistic interactions from heteronuclear paired Ni/Co dual sites lead to the optimization of the electronic structure and the reduced reaction energy barrier. This work provides a promising strategy for the synthesis of high-efficiency atomically dispersed dual-site SACs in the field of electrochemical energy storage and conversion.

Physicochemical confinement and catalytic conversion of lithium polysulfides (LiPSs) are crucial to suppress the shuttle effect and enhance the redox kinetics of lithium‐sulfur (Li‐S) batteries. In this study, a NH4Cl‐assisted pyrolysis strategy is developed to fabricate highly mesoporous N‐rich carbon (designed as NC(p)) featuring thin outer shells and porous inner networks, on which single‐Ni atoms are anchored to form an excellent sulfur host (designed as Ni‐NC(p)) for Li‐S batteries. During pyrolysis, the pyrolytic HCl from confined NH4Cl within ZIF‐8 will in situ etch ZIF‐8 to produce rich mesoporous in the carbonized product NC(p). The mesoporous Ni‐NC(p) enables favorable electron/ion transfer, high sulfur loading, and effective confinement of LiPSs, while the catalytic effect of single‐Ni species enhances the redox kinetics of LiPSs. As a result, the sulfur cathode based on the Ni‐NC(p) host delivers obviously improved Li‐S battery performance with high specific capacity, good rate capability, and cycling stability.

Prussian blue analogs (PBAs) are promising candidates for aqueous Zn‐ion batteries due to their unique open‐framework structures. However, they suffer from limited capacity and severe capacity decay originating from insufficient redox sites and structural instability. Herein, Cu‐substituted Mn‐PBA double‐shelled nanoboxes (CuMn‐PBA DSNBs) prepared by tannic acid etching and cation exchange approaches are demonstrated for efficient Zn ion storage. The unique hollow structures can expose abundant active sites and alleviate the volume change during the cycling test. Moreover, partial Cu substitution and induced Mn vacancies might inhibit the Jahn–Teller distortions of Mn‐N6 octahedra, thus contributing to the prolonged lifespan. As a result, CuMn‐PBA DSNBs exhibit high reversible capacity, decent rate performance and superior cycling stability for 2000 cycles. Furthermore, ex situ characterizations reveal that the charge storage mechanism of CuMn‐PBA DSNBs mainly involves the reversible redox reactions of transition metals and Zn2+ ion insertion/extraction processes.

Hierarchical hollow structures for electrode materials of supercapacitors could enlarge the surface area, accelerate the transport of ions and electrons, and accommodate volume expansion during cycling. Besides, construction of heterostructures would enhance the internal electric fields to regulate the electronic structures. All these features of hierarchical hollow heterostructures are beneficial for promoting the electrochemical properties and stability of electrode materials for high‐performance supercapacitors. Herein, CoO/Co‐Cu‐S hierarchical tubular heterostructures (HTHSs) composed of nanoneedles are prepared by an efficient multi‐step approach. The optimized sample exhibits a high specific capacity of 320 mAh g−1 (2300 F g−1) at 2.0 A g−1 and outstanding cycling stability with 96.5 % of the initial capacity retained after 5000 cycles at 10 A g−1. Moreover, an all‐solid‐state hybrid supercapacitor (HSC) constructed with the CoO/Co‐Cu‐S and actived carbon shows a stable and high energy density of 90.7 Wh kg−1 at a power density of 800 W kg−1.